The invention relates to a device and a process for filling containers with a liquid, in particular folded carton packings closed off at one end, comprising at least one transport device for moving the container, a storage container for holding the liquid and at least one filling head connected to the storage container and able to be closed off by a filling valve; the said filling head being vertically movable in relation to the container and being able to be lowered into this container.
Many designs of fast filling machines for filling milk, juice or similarly foaming products are known. In order to avoid a defoaming aggregate in these machines which even without it are quire complex from a design point of view, it is well known for the filling head to be movable in relation of the container in order--at the beginning of, and during, the filling process--to have as small a distance as possible between the filling head and the bottom of the container or the liquid level so as to avoid foaming.
The relative movement between container and filling head either takes place by raising and lowering the container or else by lowering and raising the filling head. In addition, a combination of both variants is possible, even though this makes little sense from a design point of view.
From CH-A-681 291 a device for filling liquids is known in which the filling head is always to be submerged evenly in the liquid. Control of this filling device is quite cumbersome because height measuring takes place by weight measuring cells. To this effect, the signals from the weight measuring cells have to be processed into weight information by an evaluation circuit. The weight information has to be processed in a computer for dose rate control to select the position of the filling valve in relation to the position of the container to be filled.
In order to minimise foaming, the task is to synchronise the mechanical movement of the container or the filling head with the filling level, because for reasons of hygiene the filling head should not be immersed in the liquid already held in the container. This task has already been solved in prior art by synchronising the lifting movement with the movement of a dose rate piston. In the case of older filling machines, synchronisation is by means of cam control; in the case of more modern machine designs, the movements of the container or of the filling head respectively, are carried out by electric servo motors, and movement synchronisation is realised by program control. Such a synchronisation of two movements is technically demanding and in addition, the use of a dose rate piston is expensive and susceptible to wear and malfunction.